Embryonic mortality (EM) is a major factor limiting reproductive efficiency in cattle, and despite negative connotations related to reproductive performance, prostaglandin F_2α (PGF_2α) is capable of being released by the uterus by Day 30 of gestation. Therefore, the objective was to evaluate differences in PGF_2α release after an oxytocin challenge between cows with high circulating concentrations of pregnancy-associated glycoproteins (PAGs) vs low PAG because of the association of increased PAG concentrations with pregnancy success. At Day 30 of gestation, pregnant cows were divided into oxytocin treatment (OT; n = 13) and control (CON; n = 12) groups. Treatment cows were further subdivided by circulating PAG concentration (high PAG, n = 7; and low PAG, n = 6). Blood samples were collected every 30 min beginning 1 h before oxytocin administration and continuing for 4 h. Prostaglandin F_2α metabolite (PGFM), progesterone, estradiol-17β (E2), and PAG concentrations were quantified. The peak concentration of PGFM occurred 2 h after oxytocin injection in treatment animals and returned to baseline levels by 4 h. No correlations were observed between PAG and PGFM, progesterone, or E2 concentrations (P > 0.05). There was no difference in initial or final PGFM concentrations between groups (P > 0.05). Progesterone and E2 concentrations decreased in cows after treatment of oxytocin (P < 0.05); however, only progesterone returned to basal concentrations by the end of the sampling period. In summary, cows with high vs low PAG concentrations at Day 30 of gestation have a similar PGFM response to oxytocin challenge.

胚胎死亡率 (EM) 是限制牛繁殖效率的主要因素，尽管与繁殖性能相关的负面含义，前列腺素 F _2α (PGF _2α ) 能够在妊娠第 30 天由子宫释放。因此，目的是评估 PGF _{2α 的}差异妊娠相关糖蛋白 (PAG) 循环浓度高的奶牛与低 PAG 的奶牛在催产素激发后释放，因为增加的 PAG 浓度与妊娠成功有关。在妊娠第 30 天，将怀孕母牛分为催产素治疗组（OT；n = 13）和对照组（CON；n = 12）。处理奶牛按循环 PAG 浓度进一步细分（高 PAG，n = 7；低 PAG，n = 6）。从使用催产素前 1 小时开始并持续 4 小时，每 30 分钟采集一次血样。前列腺素 F _2α代谢物 (PGFM)、孕酮、雌二醇-17β (E2) 和 PAG 浓度被量化。在治疗动物中注射催产素后 2 小时出现 PGFM 的峰值浓度，并在 4 小时后恢复到基线水平。在 PAG 和 PGFM、孕酮或 E2 浓度之间没有观察到相关性 ( P > 0.05)。组间初始或最终 PGFM 浓度没有差异（P > 0.05）。催产素处理后奶牛的孕酮和E2浓度降低（P < 0.05）；然而，在采样期结束时，只有孕酮恢复到基础浓度。总之，在妊娠第 30 天具有高浓度和低 PAG 浓度的奶牛对催产素激发具有相似的 PGFM 反应。